Constructor
The newly constructed object contains a copy of u.
this->buffer() == u.buffer() && this->buffer().data() != u.buffer().data()
Linear in u.size().
Strong guarantee. Calls to allocate may throw.
| Name | Thrown on | 
|---|---|
| std::length_error | u.size() > max_size(). | 
| Name | Description | 
|---|---|
| u | The url to copy. |